This Competing Continuation Application for T32 MH20031 requests support for our Institutional National Research Service Award (NRSA) in HIV prevention research at the Yale University Center for Interdisciplinary Research on AIDS (CIRA): specifically to continue a successful Post-Doctoral Fellowship Training Program (established in 1999), and to add a Pre-Doctoral Fellowship Training component. CIRA, housed within the Department of Epidemiology and Public Health at Yale University, provides an exceptional training environment. Our Training Program is unique in providing the following combination of perspectives: an interdisciplinary approach; a focus on vulnerable and underserved populations; a strong foundation of training that emphasizes methodological rigor in both quantitative and qualitative analyses; opportunities to conduct ethically-sound, community based research, domestically and internationally; and emphasis on legal, policy and ethical analysis of HIV prevention science. We are requesting support for four Pre-Doctoral and three Post-Doctoral slots per year. The Pre-Doctoral Training Program consists of: formal course work, research preceptorship, seminars, outside courses and meetings, qualifying examinations, and dissertation research. The focus of the Post-Doctoral Fellowship is "hands on" conduct of research, analysis, paper and grant writing in collaboration with a faculty mentor. Our approach to training future scientists for careers in HIV prevention research will emphasize flexibility and individual tailoring of Fellows' course work and research preceptorship, while recognizing the importance of core training in methodology and ethics. Over the past 5 years, we have successfully trained, and continue to train Post-Doctoral Fellows from a wide range of disciplines. Fellows were both exposed to, and actively collaborated in, an array of HIV prevention research projects both domestically and abroad. Part of the success of our training program can be measured by research experiences across a wide array of studies, publication records, and career trajectories. We are now prepared to add a Pre-Doctoral Training component. We are confident in our ability to prepare both Pre- and Post-Doctoral Fellows with the strongest foundation of knowledge, skills, and experience to achieve and sustain careers as scientific investigators, contributing to advances in HIV prevention, specifically, and public health, in general.